1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2016 Christoph Hellwig.
4 */
5 #include <linux/kobject.h>
6 #include <linux/blkdev.h>
7 #include <linux/blk-mq-pci.h>
8 #include <linux/pci.h>
9 #include <linux/module.h>
10
11 #include "blk-mq.h"
12
13 /**
14 * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
15 * @qmap: CPU to hardware queue map.
16 * @pdev: PCI device associated with @set.
17 * @offset: Offset to use for the pci irq vector
18 *
19 * This function assumes the PCI device @pdev has at least as many available
20 * interrupt vectors as @set has queues. It will then query the vector
21 * corresponding to each queue for it's affinity mask and built queue mapping
22 * that maps a queue to the CPUs that have irq affinity for the corresponding
23 * vector.
24 */
25 void blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,
26 int offset)
27 {
28 const struct cpumask *mask;
29 unsigned int queue, cpu;
30
31 for (queue = 0; queue < qmap->nr_queues; queue++) {
32 mask = pci_irq_get_affinity(pdev, queue + offset);
33 if (!mask)
34 goto fallback;
35
36 for_each_cpu(cpu, mask)
37 qmap->mq_map[cpu] = qmap->queue_offset + queue;
38 }
39
40 return;
41
42 fallback:
43 WARN_ON_ONCE(qmap->nr_queues > 1);
44 blk_mq_clear_mq_map(qmap);
45 }
46 EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);
47
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